The present invention relates to a device for forming groups of cigarettes.
In particular, the present invention relates to a device for the formation of cigarettes into groups, each constituting the contents of one packet. Conventionally, the basic element in a system for feeding cigarettes to a packer consists in a hopper affording a top inlet into which the cigarettes are directed en masse, horizontally and side by side, and a discharge outlet from which the cigarettes are removed in groups made up of a predetermined number.
The groups of cigarettes, appearing as a single layer or a plurality of layers positioned one on top of another, are supplied to a wrapping line by means of an intermittently driven conveyor device furnished with a plurality of uniformly distributed pockets each designed to contain a relative group. The hopper in question comprises two side walls extending parallel to the axes of the cigarettes, interconnected by two transverse walls disposed mutually parallel and separated one from the other by a distance marginally greater than the length of one cigarette. The bottom of the hopper presents at least one outlet enclosed by a horizontal plate and partitioned by substantially vertical and mutually parallel walls into a plurality of channels inside of which the massed contents of the hopper separate and form substantially vertical stacks of single cigarettes.
Considered in relation to the plate, therefore, the cigarettes appear ordered in horizontal layers each consisting in a number of cigarettes equal to the number of channels and disposed at increasing heights departing from the bottom layer, which lies in contact with the plate.
During each pause of the intermittently driven conveyor a horizontal reciprocating pusher, located on the side of the hopper remote from the conveyor, advances axially through an inlet opening afforded by one of the aforementioned transverse walls and enters into contact with one or more layers of the cigarettes, pushing them through an outlet opening afforded by the remaining transverse wall and into a pocket of the conveyor.
In this way, a group of cigarettes is formed in the pocket, consisting in a single layer or in two or more layers disposed one on top of another.
Groups consisting in a plurality of layers can also be formed by directing layers into a pocket singly and in succession, one on top of another, from a hopper with discrete discharge outlets corresponding in number to the number of layers.
In both of the cases mentioned, the cigarettes ejected from the hopper by the reciprocating pusher are caused to slide in contact with the cigarettes inside the hopper positioned immediately above the outlet, which in their turn combine to form another layer.
As a consequence of the friction generated by the sliding contact between the ejected cigarettes, which are displaced at a relatively high velocity, and the stationary cigarettes lying adjacent to them, the stationary cigarettes are urged axially against a restraint afforded by the inside face of the front transverse wall with the result that the ends can be crushed and shreds of tobacco filler lost.
Once the pusher has regained its former position, the cigarettes subjected to this damaging axial compression are free to drop into the outlet of the hopper and their inclusion in the layers displaced during the next cycle of the pusher can result in the formation of a defective group, which will be eliminated during subsequent steps of the process.
Reference has been made thus far to the case of groups consisting in a single layer and of groups consisting in a plurality of layers all comprising an identical number of cigarettes, whereas in the majority of cases the contents of a packet of cigarettes will consist in a plurality of layers comprising dissimilar numbers of cigarettes.
For instance, the contents of a soft packet of twenty cigarettes will consist generally in a group comprising two outer layers of seven cigarettes each and an intermediate layer of six cigarettes. Groups made up in this way present a particularly stable structure since the cigarettes are arranged quincuncially.
Very commonplace likewise are groups of twenty cigarettes including two contiguous layers of seven cigarettes and one outer layer of six cigarettes. Such a group will constitute the typical contents of a rigid packet with a hinged lid, given that the particular geometry enables a faultless closure of this style of packet.
Another reason for using groups formed of layers comprising different numbers of cigarettes is that in the event of an increase in production costs or of taxes, especially in countries where cigarette vending machines are in widespread use, the retail price can be maintained and the adjustment made by changing the contents of the packet, reducing the number of cigarettes in at least one layer of the group as appropriate. This naturally obviates the need to make alterations to the vending machine.
The prior art method of forming irregular groups, that is to say groups made up of layers containing different numbers of cigarettes, involves the use of pushers shaped in such a way that when entering the discharge outlet of the hopper they will engage only the cigarettes destined to make up the group.
Since however this expedient does not preclude the possibility that one or more cigarettes, albeit isolated from the action of the pusher, might be drawn forward by the adjacent cigarettes through friction and find their way into the pocket on the conveyor, the outlet of the hopper is equipped with restraints in the form of projecting fins disposed in alignment with the positions occupied by the excluded cigarettes.
Such a solution thus involves axial compression and the risk of damage to the restrained cigarettes in the same way as described previously.
It will be clear from the foregoing that the drawback described with reference to the formation of a group, whether a single layer or a plurality of layers arranged one on top of the other, all of which comprising an identical number of cigarettes, can become especially serious in the case of groups composed of layers comprising dissimilar numbers of single cigarettes, given the increased number of cigarettes that are subject to the damaging axial compression induced by the restraints.
The object of the present invention is to provide a device for forming groups of cigarettes such as will be free of the aforementioned drawbacks.
The stated object is realized according to the present invention in a device for forming groups of cigarettes, comprising a hopper through which to direct a flow of cigarettes disposed horizontally side by side and advancing each in a direction transverse to its longitudinal axis toward at least one discharge outlet of the hopper enclosed at the bottom by a substantially horizontal plate and laterally by two side walls disposed parallel to the longitudinal axis, fitted internally with a plurality of partition walls disposed substantially parallel to the side walls and defining a plurality of channels between the side walls of width equal substantially to the diameter of one cigarette, also a pocket conveyor moving transversely to the direction of the flow, and a reciprocating transfer device capable of movement in a direction parallel to the longitudinal axis through a transfer station coinciding with the outlet, by which a portion of the flow is engaged during each forward stroke and transferred from the hopper to a respective pocket to form a group.
To advantage, the device comprises restraining means designed to prevent a relative axial sliding movement of the cigarettes, acting transversely to the axis and activated during each forward stroke of the transfer device at a location coinciding with at least one of the predetermined positions occupied internally of the hopper by the cigarettes in contact with the portion of the flow engaged by the transfer device.
Another drawback that can be encountered with hoppers of the type in question is that particles of tobacco filler collect on the bottom plate and lodge between the plate and the cigarettes; this occasions incorrect positioning of the cigarettes and thus disallows the correct formation of the group of cigarettes.
A further object of the present invention is to overcome this drawback.